1. Field of the Invention
This invention relates to a photoelectric composite interconnection assembly and, particularly, to a photoelectric composite interconnection assembly with flexibility, and further relates to an electronics device using the same.
2. Description of the Related Art
The developments of high-speed and high-capacity communication technology are actively advanced with expansion of services and applications for handling high-capacity data such as picture images in telecommunication equipment such as personal computers and cellular phones. Under the circumstances, the developments of interconnections that allow high-speed and high-capacity communications at a high density inside an electronics device or among electronics devices attract attention.
A conventional electric cable 1000 with electric connectors 103 is shown in FIG. 1A wherein the same parts are designated by the identical reference numerals, respectively. In the electric cable 1000 with electric connectors 103, electric interconnections 102 are formed on a flexible substrate 101, and the electric connectors 103 are provided at both ends of the flexible substrates 101. When the flexible electric cable 1000 with the electric connectors 103 is applied, an electrical interface may be achieved freely through interconnections between substrates or electronic modules constituting electronics devices.
FIG. 1B shows an electric cable 1002 of card edge type wherein electric interconnections 102 are formed on a flexible substrate 101, and electrodes 1001 are provided at either or both of the ends of the substrate 101.
The card edge type electric cable 1002 may be fitted directly to a connector on the other end of a line without providing electric connector parts on the flexible substrate side, so that it is not required to solder the parts on the flexible substrate 101. Accordingly, a high-density and thin electric cable can be realized at a low cost.
Next, conventional optical interconnection assemblies are shown in FIGS. 2, 3, and 4, respectively.
FIG. 2 shows a constitution wherein polymer waveguides 1101 are formed on a flexible substrate 101, and further PDs 1102, amplifiers 1103 and the like are integrated, whereby optical signals are transmitted (for example, see FIG. 8, page 9 of Japanese Patent Application Laid-Open No. 9-96746).
FIG. 3 shows a constitution wherein a polymer waveguide 1201 is used as its optical transmission line, and substrates (connectors) for optical connection 1202 are provided at both ends of the polymer waveguide 1201 (for example, see FIG. 1, page 6 of Japanese Patent Application Laid-Open No. 10-186187).
FIG. 4 shows a polymer waveguide film 1303 for connecting in between an external multi-core optical connector 1301 and multi-channel optical element arrays 1302 (for example see FIG. 13, page 10 of Japanese Patent Application Laid-Open No. 2002-182048). The polymer waveguide film 1301 is provided with a connector interface 1304 connected optically with the external multi-core optical connector 1301.
However, the conventional electric interconnection assemblies or optical interconnection assemblies involve the following problems.
In the conventional electric interconnection assemblies, an electric interconnection is required to reduce its diameter with a tendency of high density. In this respect, however, an electric interconnection having a small diameter brings about a high electrical resistance. Besides, its transmission loss in high frequency becomes remarkable, so that speedup in communications is difficult. Moreover, it is also difficult to assure accurately an appropriate characteristic impedance of an electric interconnection because of a manufacturing deviation in sizing. A limit of transmission rate in this case is usually around several hundreds Mbit/second. Furthermore, there are problems of generation of electromagnetic noises or being easily affected adversely by electromagnetic noises due to an electric interconnection system. In this connection, there is an electric interconnection assembly with a coaxial structure. Although such a coaxial structure is excellent in electromagnetic noise proof strength, there is still no perfect means for solving the electromagnetic noise problem. Thus, there is a slight generation of electromagnetic noises, and even such slight electromagnetic noises, they result in a problem in telecommunication equipment wherein weak electrical signals are handled. In addition, it is difficult for the coaxial structure to achieve a miniaturization and a high-density fabrication.
On the other hand, the conventional optical interconnection assemblies have such a constitution that the polymer waveguides 1101 and optical waveguides 1104 being connected through an optical modulator 1107 thereto are formed on the flexible substrate 101, and PDs 1102, amplifiers 1103 and the like are further integrated as well as providing an electrode or electric interconnection for driving the PDs 1102, the amplifiers 1103 and the like on the flexible substrate 101 wherein optical signals are transmitted through the polymer waveguides 1001, the optical signals are photoelectric-converted in the photodetectors (PDs) 1102 to amplify the signals thus converted in the amplifiers 1103. In this case, an optical fiber 1105 is connected as an interface to the outside so as to function as an optical transmission line.
For a connecting section 1106 with the optical fiber 1105, however, a reduction in its cost is difficult, because it is necessary for an accurate position alignment of from around a submicron to several microns. In addition, there is such a problem that if a fine dust enters into the connecting section 1106, its optical connection loss becomes high, whereby a transmission quality deteriorates significantly.